Which class of fire is involved when smoke is coming from a barrel filled with rags?

The situation described, where smoke is coming from a barrel filled with rags, indicates that the fire involves combustible materials, specifically ordinary combustibles such as paper, wood, cloth, and certain types of textiles. This type of fire is categorized as Class A.

Class A fires are characterized by the burning of solid materials, primarily organic in nature. In this scenario, rags, which are typically made of fabric and likely contain organic materials, are the primary fuel source for the fire. When responding to a Class A fire, water is often an effective extinguishing agent as it cools the burning materials and reduces the heat to a point where combustion can no longer occur.

In contrast, Class B fires involve flammable liquids or gases (such as gasoline or paints), Class C fires involve energized electrical equipment, and Class D fires involve flammable metals. These categories require different methods and agents for extinguishment, underscoring why the presence of rags in this case clearly identifies it as a Class A fire.